The small bramble aphid or permanent blackberry aphid, Aphis ruborum, is widely distributed throughout Europe into North Africa and Central Asia. It is a pest of blackberry and is also found on loganberry and rarely on strawberry.
Life cycle and appearance of Small bramble aphid
Aphids have a complex life cycle, with both winged and wingless forms of adults and a great variety in colours. In greenhouses, reproduction takes place by parthenogenesis, with unfertilized viviparous females continuing to produce new generations of females. Aphids moult four times before reaching adulthood. With each moult they shed white skin, betraying their presence in the crop.
As its name indicates, the permanent blackberry aphid does not host alternate to another host for overwintering. Sexual forms appear in autumn and eggs are laid on blackberry bushes for overwintering.
Wingless females of the small bramble aphid are 1.1-2.2 mm long and usually dark-blue green in spring and pale yellow-green in summer. In early summer it lives in dense colonies which are usually attended by ants. Small winged forms appear in late summer which often live singly on the underside of leaves. These winged forms disperse to other blackberry bushes.
The colour change from spring to summer seems to be related to the colour of leaves and stems of the host plants but this does not always happen. Sometimes both colour forms can be found in the same colony.
The dense colonies appearing is early summer cause leaf curl.